Kabul: A car bomb exploded outside a sports stadium in Afghanistan's restive south on Friday, killing at least 10 people and wounding dozens more, officials said, capping a bloody week in the war-torn country.

The blast happened in Lashkar Gah city as spectators were leaving a wrestling match at the stadium, Helmand provincial governor spokesman Omar Zwak told AFP.

Helmand police spokesman Salam Afghan told AFP that at least 10 people had been killed and 35 others wounded in the attack. But Zwak put the death toll even higher at 13 dead and 45 wounded, including children.

Afghan officials often give conflicting tolls in the wake of attacks.

"The suicide bomber detonated his car bomb as spectators were leaving the stadium," Zwak said.

"The bomber wanted to go inside the stadium but he was identified by the police and he detonated himself."

The police spokesman confirmed the blast was caused by a car bomb.

Photos posted on Twitter purportedly of the explosion showed a huge fire and a thick plume of black smoke rising into the sky.

The Italian NGO Emergency said four dead and 35 wounded had been taken to its hospital in the city.